Blast furnace stack with cooling staves



April 18, 1967 l. ROSENAK 3,314,668

BLAST FURNACE STACK WITH COOLING STAVES Filed July 7, 1964 5 Sheets-Sheet l INVENTOR.

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April 18, 1967 ROSENAK 3,314,668

BLAST FURNACE STACK WITH COOLING STAVES Filed July 7, 1964 3 Sheets-Sheet 2 591W .z aevzav 25 L ATTORNEYS.

April 5 ROSENAK BLAST FURNACE STACK WITH COOLING STAVES Filed July 7, 1964 C5 Sheets-Sheet 5 INVENTOR.

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United States Patent 3,314,668 BLAST FURNACE STACK WITH COOLING STAVES Irwin Rosenak, Munster, Ind., assignor to Inland Steel Company, Chicago, Ill., a corporation of Delaware Filed July 7, 1964, Ser. No. 380,866 13 Claims. (Cl. 266-32) The present invention relates generally to blast furnaces, and more particularly to a blast furnace stack portion provided with vertically disposed cooling staves around the outside of the stack portions inner refractory lining.

The stack portion of a blast furnace is located between a furnace upper opening, through which charging material is introduced into the furnace, and a lower furnace portion in which melting takes place. The blast furnace stack is defined by an outer metallic shell (e.g. steel) Within which is located a protective lining of refractory material (e.g., several courses of refractory brick oftentimes up to four feet thick) separated from the furnace shell typically by a few inches of loam or clay. The refractory lining prevents the shell from becoming overheated.

During operation of the blast furnace, conditions within the stack, including high temperature and abrasion, wear away the brick refractory lining; and eventually the lining becomes so thin that it no longer protects the metallic shell of the stack, and the shell portion adjacent the worn lining becomes overheated. This causes a weakening of the structural properties of the overheated shell portion which normally supports higher portions of the shell and furnace. Overheating can be overcome by directing a water spray against the overheated portion of the furnace shell which in turn causes a protective layer to be built up along the interior of the shell due to the solidification of turbulent sticky material (such as hot, tacky slag), accumulating at the cooled spot along the interior of the shell. However, such makeshift protective linings necessitates subsequently operating the furnace at reduced efiiciency with resulting reduced output. Eventually, a costly complete shutdown is necessary to rebuild the brick refractory lining within the shell, and frequent shutdowns of this nature are not unusual. To lengthen the time between relinings, thicker linings would have to be used; and this decreases the amount of material which can be contained within the stack, thus reducing furnace capacity.

The present invention provides a blast furnace stack construction which eliminates hot spots on the furnace shell, reduces wear on the refractory lining, increases the capacity of the furnace, reduces the frequency of shutdowns for relining, and reduces the cost of construction of the stack over conventional constructions heretofore used.

Essentially, the invention provides a plurality of vertically disposed cooling members or staves, each of which is spaced inwardly from the inner surface of the furnace shell and each of which has an inner surface in close contacting relation with the outer surface of the refractory lining. The staves are disposed of the refractory lining and completely enclose the lining, with one or more tiers of vertically disposed staves being used to enclose at least the lower half of the stack portion of the furnace.

around the outer surface A cooling fluid is circulated through each of the staves.

Because the entire outer surface area of the refractory lining (on at least the lower part of the furnace stack) is in contact with a cooling medium, the refractory lining is maintained at a relatively low temperature compared to the temperature of the lining in situations where no=..

3,3 14,668 Patented Apr. 18, 1967 cooling medium for the lining was provided, or compared to situations where only localized cooling media were used in conjunction with the refractory lining.

With this cooling arrangement, there will be a relatively small amount of initial wear on the inner surface of the refractory lining. However, the refractory lining will be worn back only a fraction of its thickness because the more the inner surface is worn away the closer the newly exposed inner surface becomes to the cooling staves so that the temperature of the inner surface becomes lower and lower. Eventually the inner surface is worn away to a thickness whose temperature is low enough to stabilize the lining against further wearing in which temperature is a factor.

Because the lining is stabilized and relatively cool along its entire inner surface, the furnace shell is adequately protected even though the stabilized lining is relatively thin compared to the initial thickness of linings in conventional stacks not utilizing cooling media in accordance wth the present invention. Accordingly, the initial thickness of the lining need be only a fraction of the initial thickness of linings in conventional stack constructions. Therefore, in a furnace having a given outside diameter at the furnace shell, the diameter inside the thinner refractory lining will be substantially greater with resulting increased capacity for material and increased furnace output.

The staves are spaced radially inwardly, relative to the furnace shell, and the staves are mounted for radial movement, relative to the shell, in response to a radial force or pressure exerted against the staves. An outwardly directed radial force results from the pressures of thermal expansion of the refractory lining during operation of the furnace. Because the staves are in close contacting relation to the refractory lining, outward expansion on the part of the refractory lining results in corremovement on the part of the enclosing staves.

It is important that the outward pressure: exerted against the staves is not transferred thereby to the furnace shell. Accordingly, the space between the staves and the shell is either empty or is filled with a resilient material which shell.

To assure that the staves remain in close contacting relation with the outer surface of the refractory lining in all conditions of expansion or contraction of the refractory lining, and to means surrounding and enclosing the staves, and in close contacting relation with the outer surfaces of the staves. The binding means are prestressed so that an inwardly directed radial force is always exerted against the staves to hold them in close contacting relation with the refractory lining. As the refractory lining expands, causing a resulting outward movement of the staves, the binding means are elastically stretched and the stress in the bind ing means increases. Thus, the greater the outwardly directed force imparted against the staves by the refrac tory lining, the greater the inwardly directed force imparted against the staves by the binding means. The binding means has an elastic limit greater than the stress to which it will be subjected during expansion of the refractory lining and outward movement of the staves under normal operating conditions of the furnace.

The binding means may be in the form of cables, and the opposite end portions of the binding means may connect with terminal portions extending through the furnace shell and engaged by stress adjusting means located on the outside of the furnace shell. This enables periodic adjustment of the stress in the binding means to compensate for such conditions of slackness or tightness in the binding means as may periodically arise.

Because the binding means are in close contacting relation with the cooling staves, the temperature of the binding means is maintained relatively low, and problems which would arise in situations where the binding means were overheated are not a factor.

Other features and advantages are inherent in the structure claimed and disclosed or will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying diagrammatic drawings wherein:

FIGURE 1 is a fragmentary vertical sectional view of an embodiment of a blast furnace stack portion constructed in accordance with the present invention;

FIGURE 2 is a perspective view of an embodiment of a cooling stave constructed in accordance with the present invention",

FIGURE 3 is another perspective view illustrating the inner surface of the cooling stave of FIGURE 2;

FIGURE 4 is a vertical sectional view illustrating an embodiment of means for supporting stave binding means;

FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 1;

FIGURE 6 is an elevational view showing the inner surface of an embodiment of a cooling stave;

FIGURE 7 is an enlarged sectional view taken along line 7-7 of FIGURE 5 FIGURE 8 is a fragmentary elevational view, partially cut away, illustrating stress-adjusting means for the binding means;

FIGURE 9 is a sectional view taken along line 9-9 in FIGURE 4; and

FIGURE 10 is a horizontal sectional view illustrating an arrangement for connecting opposite ends of prestressed binding means.

Referring initially to FIGURES 1 and 5, there is illustrated a fragment of a blast furnace, indicated generally at 2%, and having a stack portion constructed in accordance with an embodiment of the present invention. The stack portion includes a metallic outer shell 21 and an inner refractory lining 22 located inwardly from shell 21. Spaced inwardly from shell 21, and held in close contacting relation with the outer surface 60 of refractory lining 22 by prestressed cables 26, are tiers 23, 24 each composed of a plurality of vertically disposed cooling members or staves 30.

In the illustrated embodiment lower tier 23 is supported atop a plate 65 extending inwardly from shell 21; and upper tier 24 is supported on the top 27 of lower tier 23. The number of tiers and staves, or the height of an individual stave, depends upon the vertical dimension of the portion of refractory lining 22 which it is desired to cool with the staves. The smaller the vertical dimension it is desired to cool, the fewer the tiers, or the smaller the height of an individual stave.

Surrounding and enclosing each tier of staves, and extending in continuously contacting relation with each stave and each tier of staves, is prestressed binding means such as cables 26. One or more cables 26 may be used to bind each stave 30, with FIGURE 1 illustrating an arrangement utilizing three cables for each stave. In the embodiment illustrated in FIGURES 1 and 5, each cable 26 30. Bolt 25 also serves the function of mounting a stave 30 for radial movement relative to shell 21.

Each cable 26 is prestressed (e.g., 5% of the cables elastic limit) so as to continuously exert an inwardly directed radial pressure against a tier of staves. This inrests atop a bolt 25 extending between shell 21 and stave wardly directed pressure counteracts the outwardly directed pressure resulting from the natural tendency of refractory lining 22 to expand radially outwardly during operation of the furnace. During such expansion, the

staves 30 will move radially outwardly, in conjunction with radial outward movement of the refractory lining 22, on the bolts 25. This will increase the stress on cables 26, but the cables are selected so that they have, inherently, an elastic limit substantially exceeding (e.g., by 50%) the maximum stress to which the cables will be subjected during outward movement of the staves and the refractory lining.

Shell 21 and staves 30 define a space 28 therebetween. This space may be empty or it may be filled with a resilient material which accommodates the outward movement of the staves and the refractory lining without transmitting to metallic shell 21 the outwardly directed force accompanying said movement.

Referring now to FIGURES 2, 3 and 6, each stave 30 includes an inner surface 31 all of which is in close cOntacting relation with the outer surface 60 of refractory wall 22. Stave 30 also includes respective lower and upper surfaces 32, 33 and side surfaces 34, 35. Projecting outwardly from stave 30 are three enlarged portions: a lower portion 36, a middle portion 37 and an upper portion 38. Each stave 34 includes a plurality of longitudinally or vertically extending hollow conduit portions 40, each pair of which are connected together by loops 41 in upper enlarged portion 38 and by a loop 42 in lower enlarged portion 36 (FIG. 6). This forms a continuous, vertically extending, undulating conduit in stave 30, and the opposite ends of the undulating conduit terminate at conduit connection portions 443, 44 for inlet and egress of cooling fluid to be conducted through staves 30.

Each of the enlarged portions 36-38 has a respective relatively continuous outer surface each constituting "a portion of stave outer surface 39. A cable 26, when in the assembled condition around stave 30, lies in close contacting relation to the stave and extends along surface 39 from side 34 to side 35 of the stave. Because of this continuous close contact between the cable and the stave, the cable is maintained relatively cool; and the physical properties of the cable, which might have been adversely affected at relatively high temperatures, are not affected.

Conduit inlet and outlet portions 43, 44, in the assembled arrangement, extend outwardly from staves 30, through shell 21, for connection to a conventional cooling fluid cycling arrangement (not shown). A flexible sleeve 45 is attached to the conduit portions 43, 44 on the exterior surface of shell 21, to accommodate the outward and inward movement of the conduit portions 43, 44 during outward and inward movement of stave 30. Flexible sleeve 45 maintains a seal around conduit portions 43, 44 and prevents escape of gas from a location hi lside the furnace shell to the exterior of the furnace s ell.

Referring to FIGURE 10, the stress initially imparted to cable 26 may be maintained by clamping together the ends 50, 51 of a prestressed cable 26 using permanent clamping means such as 52. In the arrangement of FIGURE 10, the entire cable, including opposite end portions 51, 52, is located inside furnace shell 21 and periodic adjustment of the stress in the cable is not practicable.

In another embodiment, illustrated in FIGURES 5 and 8, periodic adjustment of the stress in the cable is possible because opposite end portions 50, 51 are each connected to a terminal portion comprising a coupling 54 connected to a threaded rod 58 extending outwardly through an opening 55 in furnace shell 21. Enclosing opening 55 is a casing 56 having an end cap 57 through which extends the outer end portion of threaded rod 58. Threadedly engaging threaded rod portion 58, outside casing 56, are nuts 59; and located between nuts 59 and cap 57, around threaded rod portion 58, is a washer 64.

Tightening the nuts 59 on one or both of the rod portiorrs 58, increases the stress in cable 26; and loosening nuts 59 decreases the stress in cable 26. Utilizing this arrangement, the stress in cable 26 may be periodically increased or decreased, as the occasion demands, from a location outside the furnace shell.

Casing 56 is gas tight and a gas seal 65 is disposed around threaded rod portion 58 adjacent the inner surface of cap 57 on casing 56. This prevents the escape of gas, originating inside furnace shell 21, and which has passed through shell opening 55 into casing 56.

In the embodiment of blast furnace stack construction described in conjunction with FIGURES 1 and 5, the staves 30 are mounted for radial movement on bolts or rod-like members 25. However, staves 30 may be mounted for radial movement Without utilizing bolts 25. Merely arranging the staves in enclosing relationship around the refractory lining 22, with the lower tier of staves resting freely on a support, such as plate 65 in FIGURE 1, and whatever upper tier or tiers as there may he resting freely atop the lower tier (as illustrated in FIG. 1) will permit the staves to move radially relative to the furnace shell, so long as the staves are not rigidly connected in any manner to the furnace shell.

In an embodiment wherein bolts 25 are not used, means must be provided for supporting cables 26 during installation prior to the time the cables are prestressed and clamped or are connected to adjusting means so as to maintain the cables in tight contacting relation around the outer surface 29 of the staves. An embodiment of this type is illustrated in FIGURES 4 and 9 which show a bracket 66 on the outer surface of a stave 30, with cable 26 resting on bracket 66.

When bolts 25 are used for purposes of installing and mounting staves 30, in the manner previously described, an arrangement such as that illustrated in FIGURE 7 may be utilized. In this arrangement, the head 82 of bolt 25 is accommodated in a recess 80 in the inner surface 31 of stave 3t Shank 89 of bolt 25 extends through an opening 81 in stave 30, through an opening 83 in shell 21, and terminates in a threaded portion 90 around which a nut 84 is threadedly engaged. Located between nut 84 and shell 21 is sealing means 85, which may be of any conventional arrangement, and in the illustrated embodiment includes inner and outer tubular members 36, 87 and gasket 88 of resilient material.

Staves 30 are preferably composed of cast iron.

The fill in space 28, between shell 21 and staves 30, need not be a refractory material, because the temperature in space 23 is relatively low; but fill should be resilient to accommodate the outward movement of the staves and to absorb the outwardly directed pressures of said outward movement without transferring the outwardly directed pressures to the furnace shell. The fill in space 28 is preferably a material which prevents channelling of gases in space 28. The fill material may be a cellular, particulate material; it may be polyurethane foam; or it may be blankets of glass fiber.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. In a blast furnace:

a metallic furnace outer shell;

a refractory lining spaced inwardly of said shell;

a vertically disposed metallic cooling stave having an outer surface spaced inwardly from said shell and an inner surface in close contacting relation to the outer surface of said refractory lining;

means mounting said stave for radial movement, relative to the shell, in response to a radially directed pressure exerted against said stave;

means, including conduit means, for circulating a cooling fluid through said cooling stave;

means between said cooling stave and said furnace shell for accommodating expansion of the refractory lining and movement of the cooling stave in an outward direction toward the furnace shell and for absorbing the outwardly directed pressure resulting from said expansion without transferring said outwardly directed pressure to the furnace shell; prestressed binding means located inside the shell and extending in close contacting relation to the outer surface of said stave, from one side edge to the other side edge of said stave, and exerting an inwardly directed pressure against the stave; said binding means including a portion thereof in heat-conducting relation with the stave, from one side edge to the other side edge of the stave;

sai-d binding means having an elastic limit exceeding the stress to which the binding means is subjected at the maximum outward expansion of the refractory lining and cooling stave under normal operating conditions of said furnace.

2. In a blast furnace as recited in claim ing:

terminal means at each opposite end portion of said binding means, extending through said furnace shell to a location outside the furnace shell;

and means located on the outside of the furnace shell engaging said terminal means for adjusting the stress in said binding means.

3. In a blast furnace as recited in claim 2 wherein:

said furnace shell includes a pair of openings through each of which extends a respective terminal means; and gas-sealing means for preventing leakage of gas from inside the shell through said shell openings.

4. In a blast furnace as recited in claim 2 wherein:

said binding means comprises prestressed cable means;

and said adjusting means comprises means, engaging said terminal means, for exerting a pull on said cable. 5. In a blast furnace as recited in claim 1 and comprising:

rod-like means for mounting spaced relation to said shell;

said rod-like means including one end portion extending to the furnace shell and another end portion extending to said stave;

said stave including means mounting the stave for slidab-le movement along the rod-like means.

6. In a blast furnace as recited in claim 5 wherein:

said shell has an opening through which extends said one end portion of the rod-like means;

means located outside the shell for engaging said one end portion;

and gas-sealing means for preventing escape of gas from inside the shell through said opening for the rod-like means.

7. In a blast furnace as recited in claim 1 wherein said expansion-accommodating means comprises a solid, resilient material including means for preventing gas channeling between the stave and the shell.

8. In a blast furnace as recited in claim 1 wherein said stave is composed of cast iron and includes:

a top surface, a bottom surface and a pair of side surfaces;

said inner surface of the stave having a relatively large 60 area compared to the areas of said top, bottom and side surfaces; substantially the entire area of said inner surface being in close contacting relation to the refractory lining. 9. In a blast furnace as recited in claim 1 wherein: said binding means is prestressed about 5% of the elastic limit thereof; and said elastic limit of the binding means is at least 50% greater than said stress to which the binding means is subjected at said maximum outward expansion. In a blast furnace: a metallic furnace outer shell; a refractory lining spaced inwardly of said shell; a plurality of vertically disposed metallic cooling staves 1 and comprissaid stave in inwardly 7 arranged in side-by-side relation around the outside of said refractory lining and enclosing said lining;

each of said cooling staves having an outer surface spaced-inwardly from said shell and an inner surface in close contacting relation to the outer surface of said refractory lining;

means mounting said staves for radial movement, relative to the shell, in response to a radially directed pressure exerted against the staves;

means, including conduit means, for circulating a cooling fluidthrough said cooling staves; means between said cooling staves and said furnace shell for accommodating expansion of the refractory lining and movement of the cooling staves in an outward direction toward the furnace shell and for absorbing the outwardly directed pressure resulting from said expansion without transferring said outwardly directed pressure to the furnace shell;

prestressed binding means located inside the shell and extending around the refractoryenclosing staves, with at least the greater portion of said binding means :being in close contacting relation to the outer surfaces of said staves, and exerting an inwardly directed pressure against the staves;

at least the greater portion of said binding means being in heat-conducting relation with the staves;

said binding means having an elastic limit exceeding the stress to which the binding means is subjected at the maximum outward expansion of the refractory lining and the cooling staves under normal operating conditions of said furnace.

-11. In a blast furnace as recited in claim 10 wherein:

said binding means comprises prestressed steel cable means;

said furnace including means located outside the staves for adjusting the stress in said cable means.

12. In a blast furnace as recited in claim 119 wherein said staves are in continuous contacting relation with the refractory lining along at least the entire lower half of the blast furnace stack.

13. In a blast furnace:

a metallic furnace outer shell;

a refractory lining spaced inwardly of said shell;

a vertically disposed metallic cooling stave having an outer surface spaced inwardly from said shell and an inner surface in close contacting relation to the outer surface of said refractory lining;

means mounting said stave for radial movement, rela tive to the shell, in response to a radially directed pressure exerted against said stave;

means, including conduit means, for circulating a cooling fluid through said cooling stave;

a space between said cooling stave and said furnace shell for accommodating expansion of the refractory lining and movement of the cooling stave in an outward direction toward the furnace shell without transferring the outwardly directed pressure resulting from said expansion to the furnace shell;

prestressed binding means located inside the shell and extending in close contacting relation to the outer surface of said stave, from one side edge to the other side edge of said stave, and exerting an inwardly directed pressure against the stave;

said binding means including a portion thereof in heatconducting relation with the stave, from one side edge to the other side edge of the stave;

said binding means having an elastic limit exceeding the stress to which the binding means is subjected at the maximum outward expansion of the refractory lining and cooling stave under normal operating conditions of said furnace.

References Cited by the Examiner UNITED STATES PATENTS JOHN F. CAMPBELL, Primary Examiner.

4 M. L. FAIGUS, Assistant Examiner. 

1. IN A BLAST FURNACE: A METALLIC FURNACE OUTER SHELL; A REFRACTORY LINING SPACED INWARDLY OF SAID SHELL; A VERTICALLY DISPOSED METALLIC COOLING STAVE HAVING AN OUTER SURFACE SPACED INWARDLY FROM SAID SHELL AND AN INNER SURFACE IN CLOSE CONTACTING RELATION TO THE OUTER SURFACE OF SAID REFRACTORY LINING; MEANS MOUNTING SAID STAVE FOR RADIAL MOVEMENT, RELATIVE TO THE SHELL, IN RESPONSE TO A RADIALLY DIRECTED PRESSURE EXERTED AGAINST SAID STAVE; MEANS, INCLUDING CONDUIT MEANS, FOR CIRCULATING A COOLING FLUID THROUGH SAID COOLING STAVE; MEANS BETWEEN SAID COOLING STAVE AND SAID FURNACE SHELL FOR ACCOMMODATING EXPANSION OF THE REFRACTORY LINING AND MOVEMENT OF THE COOLING STAVE IN AN OUTWARD DIRECTION TOWARD THE FURNACE SHELL AND FOR ABSORBING THE OUTWARDLY DIRECTED PRESSURE RESULTING FROM SAID EXPANSION WITHOUT TRANSFERRING SAID OUTWARDLY DIRECTED PRESSURE TO THE FURNACE SHELL; PRESTRESSED BINDING MEANS LOCATED INSIDE THE SHELL AND EXTENDING IN CLOSE CONTACTING RELATION TO THE OUTER SURFACE OF SAID STAVE, FROM ONE SIDE EDGE TO THE OTHER SIDE EDGE SAID STAVE, AND EXERTING AN INWARDLY DIRECTED PRESSURE AGAINST THE STAVE; SAID BINDING MEANS INCLUDING A PORTION THEREOF IN HEAT-CONDUCTING RELATION WITH THE STAVE, FROM ONE SIDE EDGE TO THE OTHER SIDE EDGE OF THE STAVE; 